Radical polymerizable composition

ABSTRACT

A radical polymerizable composition comprising 
     (A) a compound having a pi-electron conjugated structure and 
     (B) a radical polymerizable compound, which is useful for molding into an arbitrary shape, which can be rendered electrically conductive and which is, therefore, useful as a material for electrodes or circuits in the electrical and electronic industry.

This is a divisional of application No. 07/160,431 filed Feb. 25, 1988,now U.S. Pat. No. 4,962,158.

FIELD OF THE INVENTION

This invention relates to a radical polymerizable composition suitableas materials for use in electrical and electronic fields, e.g.,materials for electrodes of capacitance video discs, batteries,condensers and display elements, materials for electrochromic displayelements, circuit materials of printed circuit boards and the like.

BACKGROUND OF THE INVENTION

Requirements for various conductive materials to be used in the electricand electronic industry are becoming more severe. Development ofconductive materials which would achieve a reduction in weight and sizeof parts and exhibit long-term stability and high performance propertieshas long been demanded.

In order to cope with these increasing requirements, extensive researchhas recently been conducted on electrically conductive high polymers inplace of the conventional carbonaceous or metallic materials. Manyproposals on use of such high polymers have also been made. Conductivehigh polymers so far proposed include heterocyclic high polymers, suchas polythiophene, polypyrrole, etc., as described in U.S. Pat. Nos.4,543,402, 4,547,270, 4,552,927, 4,548,696 and 4,657,985, and they havebeen suggested as applicable to electrodes for secondary batteries orelectrochromic display elements.

However, many of these heterocyclic high polymers are insoluble orinfusible. Therefore, they have such poor molding processability thatthey have not been employed practically. In order to overcome thisproblem, various techniques have recently been proposed. For example, J.C. S., Chem. Commum., p. 817 (1984) discloses a method for obtaining auniform composite film composed of polypyrrole and a thermoplasticresin, such as polyvinyl chloride, in which the surface of an anode baseis previously coated with a thermoplastic resin film before polypyrroleis produced by electrolytic polymerization. European Patent ApplicationNo. 160207A discloses that electrolytic polymerization of pyrrole iscarried out in the presence of a polymer latex having anionic surfacecharacteristics to obtain a conductive high polymer composite materialwith improved processability. Similar methods are also disclosed in U.S.Pat. Nos. 4,582,575, 4,604,427, 4,617,353, and 4,617,228. Further,Synthetic Metals, Vol. 15, p. 169 (1986) teaches introduction of a longchain alkyl group into insoluble and infusible heterocyclic highpolymers t thereby obtain organic solvent-soluble heterocyclic highpolymers which can be molded into a coating film on an appropriate base.As exemplified by the above-mentioned techniques, the conventionalproposals describe how to combine a previously polymerized resin and aconductive high polymer to obtain a composite film.

However, a composite material of a previously polymerized resin and aconductive high polymer is nothing but a polymer blend. It is difficultto form a microscopically uniform composite film. In other words, it isdifficult to obtain a composite film having high electric performancecharacteristics.

In the electric and electronic industry, it has recently becomewidespread to coat a radical polymerizable compound and polymerize it byirradiation with, for example, ultraviolet radiation to thereby effectminute processing. However, the above-described composite formationtechniques have difficulties in minute processing unless extremelycomplicated steps are involved and, moreover, the resolving powerattained has its limit.

SUMMARY OF THE INVENTION

An object of this invention is to provide a radical polymerizablecomposition which can be molded into an arbitrary shape and can berendered electrically conductive.

The above object of this invention is accomplished by a radicalpolymerizable composition comprising

(A) a compound having a pi-electron conjugated structure and

(B) a radical polymerizable compound.

The Compound having a pi-electron conjugated structure according to thepresent invention is a compound having a repeating unit represented byformula (I) or (II): ##STR1## wherein X represents NH, S, O, Se Or Te;Y₁, Y₂, Y₃, and Y₄, which may be the same or different, each representsa hydrogen atom, a substituted or unsubstituted alkyl group having from1 to 12 carbon atoms, an alkoxy group, an alkoxycarbonyl group, anaryloxycarbonyl group, an alkoxysulfonyl group, an aryloxysufonyl group,or an amido group; and the parentheses indicate repeating units.

DETAILED DESCRIPTION OF THE INVENTION

In formulae (I) and (II), the alkyl group for Y₁ to Y₄ is a straight orbranched chain alkyl group with or without a substituent such as analkoxycarbonyl group, an aryloxycarbonyl group, an alkoxysulfonyl group,an aryloxysulfonyl group, or an amido group (e.g., a monoalkylamidogroup, a dialkylamido group, and a monoarylamido group). The alkyl grouphas from 1 to 12 carbon atoms, preferably from 4 to 12 carbon atoms, andmore preferably from 6 to 10 carbon atoms (including the number ofcarbon atoms in the substituent if any). When the alkyl group issubstituted with an alkoxy- or aryloxycarbonyl group, an alkoxy- oraryloxysulfonyl group, or an amido group, the substituted alkyl grouppreferably has from 3 to 8 carbon atoms. Examples of the alkyl groupinclude --C₆ H₁₃, --C₈ H₁₇, --C₁₀ H₂₁, --CH₂ CH₂ COOCH₃, --CH₂ CH₂ --SO₃CH₃, and --CH₂ CH₂ CONHCH₃. The alkoxy group for Y₁ to Y₄ has a straightor branched chain alkyl moiety preferably having from 1 to 4 carbonatoms such as --OCH₃ and --OC₂ H₅. Examples of the other groups for Y₁to Y₄ include --COOCH₃, --SO₃ CH₃, etc. Of these groups for Y₁ to Y₄,preferred are a hydrogen atom, a substituted or unsubstituted alkylgroup, and an alkoxy group.

Preferred for X in formula (I) are --NH--and --S--.

The compound having a pi-electron conjugated structure may have two ormore repeating units represented by formula (I), or two or morerepeating units represented by formula (II). Further, the compoundhaving a repeating unit(s) of formula (I) may be used as a mixture withthat having a repeating unit(s) of formula (II).

The compound having a pi-electron conjugated structure preferably has anaverage degree of polymerization (the number of the repeating unit) offrom 5 to 10,000, more preferably from 50 to 10,000 and most preferablyfrom 100 to 1,000, provided that, when Y₁, Y₂, Y₃, and Y₄ in therepeating unit of formula (I) or (II) are a hydrogen atom and/or anunsubstituted alkyl group having 1 to 3 carbon atoms, the average degreeof polymerization preferably ranges from 5 to less than 50 and morepreferably from 8 to 20.

Preferred terminal groups in the compound having the repeating unit offormula (I) or (II) are monovalent groups derived from the groupsrepresented by formula (I) or (II), respectively, such as ##STR2##wherein X, Y₁, Y₂, Y₃, and Y₄ are defined above.

Of the compounds having a repeating unit represented by formulae (I) or(II), preferred compounds are those soluble in radical polymerizablecompounds or organic solvents, for example, oligomers of thiophene,pyrrole, aniline, etc., heterocyclic high polymers having varioussubstituents introduced therein, and polyaniline having varioussubstituents introduced therein. The most preferred of them arepoly[2,5-thienylene-3-(methyl 2-ethanesulfonate)],poly(2,5-dimethoxyaniline), poly(3-hexyl-2,5-thienylene),poly(3-methoxythiophene), andpoly[2,5-pyrrole-1-(methyl-2-butanesulfonate)].

The compound having a pi-electron conjugated structure can be producedby conventional methods such as electrolytic polymerization described,for example, in U.S. Pat. Nos. 4,552,927, 4,548,696 and 4,582,575, aswell as chemical polymerization described in U.S. Pat. Nos. 4,604,427,4,617,353, and 4,617,228.

These compounds having a pi-electron conjugated structure can berendered conductive by subjecting a part of the compound to oxidation orreduction, i.e., doping. Suitable techniques for accomplishing such aredescribed, e.g., in Kagaku Zokan, Vol. 87, "Gosei Kinzoku", Kagaku DojinK.K. and Handbook of Conducting Polymers, Vol. 1 chapter 2, p. 45-79,Marcel Dekker Inc. (1986).

The doping can be effected either chemically or electrochemically. Inchemical doping, various known electron accepting compounds or electrondonating compounds can be used as a dopant, such as (i) halogens, e,g.,iodine, bromine, and bromine iodide, (ii) metal halides, e.g., arsenicpentafluoride, antimony pentafluoride, silicon tetrafluoride, phosphoruspentachloride, phosphorus pentafluoride, aluminium chloride, aluminiumbromide, and aluminium fluoride, (iii) protonic acids e.g., sulfuricacid, nitric acid, fluorosulfuric acid, trifluoromethanesulfuric acid,and chlorosulfuric acid, (iv) oxidants, e.g., sulfur trioxide, nitrogendioxide, and difluorosulfonyl peroxide, (v) AgClO₄ (vi)tetracyanoethylene, tetracyanoquinodimethane, chloranil,2,3-dichloro-5,6-dicyano-p-benzoquinone, and 2,3-dibromo5,6-dicyano-p-benzoquinone, and (vii) alkali metals, e.g., Li, Na, andK. In electrochemical doping, examples of dopant include (i) aniondopants such as halide anions of the Va or IIIa Groups elements, (e.g.,PF₆ ⁻, SbF₆ ⁻, AsF₆ ⁻, SbCl₆ ⁻ and Bf₄ ⁻), halogen anions (e.g., I⁻ (I₃⁻), Br⁻, and Cl⁻), and perchlorate anions (e.g., ClO₄ ⁻) and (ii) cationdopants such as alkali metal ions (e.g., Li⁺, Na⁺, K⁺, Rb⁺ and Cs⁺), andcations represented by R_(4-x) M⁺ H_(x) or R₃ M'⁺ (wherein R is an alkylgroup of 1 to 10 carbon atoms or an aryl group (e.g., a phenyl group, ahalophenyl group, and an alkylphenyl group), M is N, P, or As, M' is Oor S, and x is 0 or 1) (e.g., tetraalkylammonium, tetraalkylphosphonium,tetraalkylarsonium, trialkyloxonium, and trialkylsulfonium). In thepresent invention, however, dopants are not limited thereto.

The content of dopant in the compound having a pielectron conjugatedstructure is not particularly limited, but it is preferably from 0.05 to1, more preferably from 0.1 to 0.4, per one repeating unit. By thedoping operation the compound having a pi-electron conjugated structurecan exhibit a direct current electroconductivity of more than 10⁻⁵ S/cmand preferably more than 10⁻³ S/cm.

The radical polymerizable compound which can be used in the presentinvention include various ethylene derivatives, e.g., as described inJugo Han-noron Koza, Vol. 1, "Radical Polymerization (I)", pp. 5-9, suchas styrene derivatives (e.g., styrene, divinylbenzene andp-chloromethylstyrene); acryltes (e.g., methyl acrylate, epoxy acrylate,and trimethylolpropane triacrylate); methacrylates (e.g., methylmethacrylate and epoxy methacrylate); allyl compounds and allylidenecompounds (e.g., diallylidene pentaerythritol and allyl chloride);vinylamides, vinylimides, vinyllactams, and vinylcarbazoles (e.g.,N-vinylpyrrolidone); and acrylamides (e.g., acrylamide andmethacrylamide). Of these, acrylates are preferred, and epoxy acrylatesare particularly preferred. These radical polymerizable compounds may beused either individually or as combinations of two or more thereof.

The mixing ratio of the compound having a pielectron conjugatedstructure and the radical polymerizable compound is not particularlylimited. In order to ensure sufficient characteristics, it is desirablethat the compound having a pi-electron conjugated structure of thepresent invention is contained in an amount of from 5 to 50% by weight,more preferably from 10 to 30% by weight, based on the total weight ofthe compound having a pi-electron conjugated structure and the radicalpolymerizable compound.

The method for mixing the components is not particularly restricted. Itis desirable for the compound having a pi-electron conjugated structureto be dispersed as uniformly as possible in the composition. To thiseffect, the mixing may be carried out in a molten state under heating orin the presence of an appropriate solvent in which the components arehomogenized and the solvent is then removed. In the latter case,polymerization may be effected without removing the solvent. Examples ofthe solvent include chloroform, methylene chloride, chlorobenzene,tetrahydrofuran, N-methylpyrrolidone, N,N-dimethylformamide,dimethylsulfoxide, and propylene carbonate.

The radical polymerizable composition may contain conventionaladditives, for example, a radical polymerization initiator such asperoxides (e.g., hydrogen peroxide, benzoyl peroxide, ammoniumpersulfate, and cumene hydroperoxide), azo compounds (e.g.,azobisisobutyronitrile and azodibenzoyl), and carbonyl compounds (e.g.,benzophenone and benzoin isopropyl ether); and a radical polymerizationpromoter such as amines capable of promoting decomposition of peroxides(e.g., N,N-dimethylaminoethanol and dimethylaniline).

The radical polymerizable composition according to the present in entioncan be applied to surfaces of various solid bases, such as metals,semiconductors, synthetic resins, ceramics, paper, fibers, and the like,by coating, spraying, deposition, or like technique to form a coatingfilm. The composition of the invention can also be cast and dried ineither a batch system or a continuous system to produce a film of anydesired thickness. Further, the composition may be polymerized in a moldof various shapes to produce molded articles.

The radical polymerizable composition of the present invention can bepolymerized by using various sources of energy such as heat, ultravioletrays, electron rays, X-rays, etc., without any particular limitations.Polymerization with ultraviolet or electron radiation is suitablyemployed because of easy operation and satisfactory resolving powerattained in pattern formation.

The radical polymerizable composition of the present invention may berendered conductive by doping, either before polymerization or afterpolymerization. It should be noted, however, that many compounds havinga pielectron conjugated structure tend to have their solubility insolvents reduced upon doping so that the latter manner, i.e.,polymerization followed by doping is preferred for obtaining polymershaving satisfactory electrical characteristics.

The radical polymerizable composition according to the present inventioncan be used as a material of electrodes of capacitance video discs.Although there is a fine roughness on the surface of video discs, areplica of high precision can be prepared using the composition of thepresent invention due to its satisfactory fluidity. In addition,photocuring techniques can be applied to the composition to greatlyincrease productivity as compared with the conventional methods.

Use of the radical polymerizable composition of the invention also makesit possible to form a circuit of a minute pattern directly from aconductive polymer by utilizing the photoresist technique.

Further, when the composition of the invention is applied toelectrochromic display elements, pattern formation can be carried outeasily and the resulting display elements have improved durabilitybecause of a small rate of elution.

The radical polymerizable composition according to the present inventionis characterized by its satisfactory processability and can be used in avariety of applications taking advantage of its characteristics.

The present invention is now illustrated in greater detail withreference to Examples, but it should be understood that the presentinvention is not deemed to be limited thereto. Unless otherwiseindicated herein, all parts, percents, ratios and the like are byweight.

EXAMPLE 1

One gram of thiophene oligomer (average degree of polymerization: about12) was dissolved under heating in a mixture consisting of 5 g of anepoxy acrylate resin ("Ripoxy sp-1509" produced by Showa Kobunshi K.K.),4 g of trimethylolpropane triacrylate ("NK ESTER TMPT" produced byShin-nakamura Kagaku Kogyo K.K.), 1 g of N-vinyl-2-pyrrolidone, 0.2 g ofbenzophenone (radical polymerization initiator), and 0.2 g ofN,N-dimethylaminoethanol (radical polymerization promoter) to prepare auniform deep red solution.

The resulting solution was coated on a ITO glass plate (Indium-Tin-Oxidecoated glass; prepared by vapor-depositing on a glass plate indium oxidewith tin dopant) to a film thickness of 10 μm and irradiated withultraviolet light in air using a high-pressure mercury lamp (output: 75W/cm) to prepare a coated electrode.

An electrochemical cell was constructed from the coated electrode as aworking electrode, a platinum plate as an opposing electrode, asilver/silver ion electrode as a reference electrode, and a 1.0 mol/lsolution of tetraethylammonium perchlorate in acetonitrile.

When a potentiostat was connected to the cell, and electrochemicaldoping was carried out at a potential of +0.8 V based on the referenceelectrode, the deep red cured film turned deep blue. The coatedelectrode was then removed from the cell, thoroughly washed withacetonitrile, and stripped from the ITO glass plate. The surfaceresistivity of the cured film was found to be 530 Ωsq.

EXAMPLE 2

One gram of poly[2,5-thienylene-3-(methyl 2-ethanesulfonate] (averagedegree of polymerization: about 50) was poured into a solution of 1.0 gof nitrosyl hexafluorophosphate in 10 ml of nitromethane to effectchemical doping with PF₆ ⁻, whereby a deep blue solution was obtained.The solution was uniformly mixed with a mixture having the samecomposition as used in Example 1, except that no thiophene oligomer wasused, and the nitromethane was removed therefrom by distillation underreduced pressure.

The resulting mixture was coated on a glass slide to form a thin filmand irradiated with ultraviolet light in the same manner as in Example 1to prepare a cured film. The film was found to have a surfaceresistivity of 360 Ω/sq.

EXAMPLE 3

One gram of an aniline oligomer (average degree of polymerization: about8) was dissolved in 10 ml of N,N-dimethylformamide. The solution wasmixed with a mixture having the same composition as in Example 1, exceptthat no thiophene oligomer was present, to form a uniform solution. Thedimethylformamide was removed therefrom by distillation under reducedpressure.

The resulting composition was coated on a glass slide and irradiatedwith ultraviolet light in the same manner as in Example 1 to obtain acured film. When hydrogen chloride gas was applied to the cured film,the film changed from a blackish blue to green and had a surfaceresistivity of 2.3 kΩ/sq.

EXAMPLE 4

One gram of poly(2,5-dimethoxyaniline) (average degree ofpolymerization: about 50) was dissolved in 10 ml of acetonitrile. Thesolution was mixed with a mixture having the same composition as inExample 1 except that the thiophene oligomer was not present, and theresulting composition was coated and cured, followed by doping, in thesame manner as in Example 3. The resulting cured film had a bluish greencolor and a surface resistivity of 5.0 kΩ/sq.

EXAMPLE 5

Five grams of poly(3-hexyl-2,5-thienylene) (average degree ofpolymerization: about 500) was dissolved under heating in a mixtureconsisting of 10 g of an epoxy acrylate resin ("Ripoxy R-806" producedby Showa Kobunshi K.K.) and 20 g of styrene to prepare a uniform redsolution. 1.5 g of benzoin isopropyl ether (radical polymerizationinitiator) was further added to the solution.

The resulting solution was coated on a glass slide in a thickness of 20μm and irradiated with ultraviolet light in air using a high-pressuremercury lamp (output: 75 W/cm) to prepare a cured film. Then, the curedfilm was exposed to iodine vapor to effect doping. The surfaceresistivity of the film was 150 Ω/sq.

EXAMPLE 6

1.5 g of poly(2,5-dimethoxyaniline) (average degree of polymerization:about 100) doped with p-toluenesulfonic acid was mixed under heatingwith a spiroacetal resin ("Spilac N-4N-7" produced by Showa KobunshiK.K.), to which 0.2 g of benzoin isopropyl ether was further added toprepare a uniform solution.

Using the resulting solution, the same procedure as in Example 5 wasrepeated to obtain a doped cured film having a surface resistivity of750 Ω/sq.

While the invention has been described in detail and with reference tospecific embodiments thereof, it will be apparent to one skilled in theart that various changes and modifications can be made therein withoutdeparting from the spirit and scope thereof.

What is claimed is:
 1. A radical polymerizable composition comprising(A)a compound having a pi-electron conjugated structure with a repeatingunit represented by formula (II) ##STR3## wherein Y₁, Y₂, Y₃ and Y₄,which may be the same or different, each represents a hydrogen atom, asubstituted or unsubstituted alkyl group having from 1 to 12 carbonatoms, an alkoxys group, an alkoxycarbonyl group, an aryloxycarbonylgroup, an alkoxysulfonyl group, an aryloxysulfonyl group or an amidogroup; and the parenthesis indicate a repeating unit, and the number ofrepeating units in said compound (A) ranges from 5 to 10,000 and (B) aradical polymerizable compound.
 2. A radical polymerizable compositionas claimed in claim 1, wherein said compound (A) is an aniline oligomeror poly(2,5-dimethoxyaniline).
 3. A radical polymerizable composition asclaimed in claim 2, wherein said compound (A) ispoly(2,5-di-methoxyaniline) represented by the formula: ##STR4## whereinthe parentheses indicate a repeating unit.
 4. A radical polymerizablecomposition as claimed in claim 1, wherein Y₁, Y₂, Y₃, and Y₄, eachrepresents a hydrogen atom, a substituted or unsubstituted alkyl grouphaving from 3 to 12 carbon atoms, or an alkoxy group having from 1 to 4carbon atoms.
 5. A radical polymerizable composition as claimed in claim1, wherein the number of repeating units in said compound (A) rangesfrom 50 to 10,000, provided that, when Y₁, Y₂, Y₃, and Y₄ in therepeating unit of formula (II) are a hydrogen atom and/or anunsubstituted alkyl group having from 1 to 3 carbon atoms, the number ofrepeating units ranges from 5 to less than
 50. 6. A radicalpolymerizable composition as claimed in claim 1, wherein said compound(B) is styrene, epoxyacrylate, diallylidene pentaerythritol, epoxymethacrylate, trimethylolpropane triaacrylate, methyl methacrylate,N-vinylpyrrolidone, or a mixture thereof.
 7. A radical polymerizablecomposition as claimed in claim 1, wherein said compound (A) is presentin an amount of from 5 to 50% by weight based on the total weight ofsaid compound (A) and said compound (B).
 8. A radical polymerizablecomposition as claimed in claim 7, wherein said compound (A) is presentin an amount of from 10 to 30% by weight based on the total weight ofsaid compound (A) and said compound (B).
 9. A radical polymerizablecomposition comprising:(A) a compound having a pi-electron conjugatedstructure with a repeating unit represented by formula (II) ##STR5##wherein Y₁, Y₂, Y₃, and Y₄, which may be the same or different, eachrepresents a hydrogen atom, a substituted or unsubstituted alkyl grouphaving from 1 to 12 carbon atoms, an alkoxy group, an alkoxycarbonylgroup, an aryloxycarbonyl group, an alkoxysulfonyl group, anaryloxysulfonyl group or an amide group; and the parenthesis indicate arepeated unit; and the number of repeating units in said compound (A)ranges from 5 to 10,000; (B) a radical polymerizable compound; and (c) aradical polymerization initiator.
 10. A radical polymerizablecomposition as claimed in claim 9, wherein said radical polymerizationinitiator is selected from the group consisting of a peroxide, an azocompound and a carbonyl compound.